Thermoplastic conjugate fibers, for example, PE/PP, PE/PET, PP/PET, and so forth, are used for the surface layer of adsorbent products such as sanitary napkins and for the wiping elements of mops and wiping materials for cleaning applications. Webs formed by spreading a continuous fiber bundle can be used for them.
In a continuous fiber bundle, crimped continuous fibers are gathered so as to cohere with each other, thereby providing a high fiber density. When this continuous fiber bundle is to be processed into the previously mentioned surface layer or wiping member, the production sequence proceeds through a step in which the continuous fibers constituting the fiber bundle are separated from each other in the width direction to broaden out the bulk width, that is, a spreading step. A web in which the continuous fibers have been loosened from each other, and thus which has a low fiber density, can be obtained by this spreading step from a high fiber density fiber bundle in which the continuous fibers are bundled or gathered with each other. The surface layer or wiping element is produced from the resulting web having an approximately uniform thickness and handle in the width direction.
Various tactics are employed in order to obtain a uniform web by the spreading of a fiber bundle. For example, Patent Reference 1 teaches that a fiber bundle having sensible crimps and/or latent crimps, a single filament fineness of 0.5 to 100 denier, a total fineness of 10,000 to 300,000 denier, and a sensible crimp count of 10 to 50 peaks/25 mm, provides a suitable range for the spread width upon draw-spreading and can be uniformly spread at high speeds and thereby provides a web with an excellent handle at high productivities. However, a fiber bundle that exhibits a more stable spreading behavior has been in demand.
[Patent Reference 1] Japanese Patent Application Publication No. 1109-273037